Pipeline joint infill and protective sleeve

ABSTRACT

An apparatus for protecting exposed pipeline joints on weight coated pipelines used in offshore applications includes a pliable cover sleeve which overlaps a pair of weight coat sections that surround the pipeline on each side of the pipe joint. The cover sleeve circumferentially envelops the pipe joint, forming an annular space enclosed between the pipe and the cover sleeve and bordered by the pair of weight coat sections. The cover sleeve includes a number of protruding ridges forming a number of chambers between the ridges in flow communication with the annular space. A joint-filling material of polyurethane foam formed by polyurethane chemicals fills the annular space and the chambers between the ridges of the cover sleeve. As the joint filling material hardens it interlocks with the ridges of the cover sleeve, securing the joint filling material between the cover sleeve and the pipe joint.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of co-pending,commonly owned U.S. patent application Ser. No. 10/943,578 filed Sep.17, 2004.

FIELD OF THE INVENTION

The present invention relates generally to the protection of exposedpipeline joints of pipelines used in offshore operations, and relatesmore particularly to a pliable protective cover sleeve securing thereina protective substance in order to protect a pipe joint.

BACKGROUND

It is conventional in the offshore pipeline industry to use weightcoated pipe for pipelines which are used on ocean floors or otherunderwater surfaces. The weight coats traditionally have been made ofdense materials such as concrete, and are typically several inches thickaround the circumference of the pipe. The weight coats protect thepipeline and provide sufficient weight to maintain the pipelinesubmerged in a non-buoyant condition.

In most cases, the weight coats are applied to the full length of thepipe except for a short distance where there is a bare pipe end portion,approximately one foot from the end of each pipe section. The endportion of the pipe remains without the weight coat to facilitatewelding together individual sections of the weight coated pipe in orderto make up the pipeline. In this manner, sections of pipe are placed ona barge and welded sequentially onto preceding sections forming apipeline extending from the barge. The newly formed pipeline is placedon rollers, and as the barge moves forward, the pipeline is carried overthe rollers, then lowered, and then laid on the bed of the body ofwater.

The portions of pipe not having a weight coat had a corrosion coatingapplied to the surface of the pipe to prevent the pipe from corrodingdue to exposure to the elements. Generally, the corrosion coatings usedwere a heat shrinking tape or a fusion bonded epoxy. After the sectionsof pipe were welded together, various techniques were used to protectthe corrosion coating on the exposed portions of pipe around each joint.

One prior known procedure was to wrap sheet metal over the weightcoating adjacent the exposed portion of the pipe and band the sheetmetal in place with metal bands. Generally, a zinc coated sheet metalwas used. The space between the pipe and sheet metal was then filledwith a molten material which would solidify as it cooled. However, inmost cases, the pipeline had to be in a condition for handlingimmediately after the sleeves were filled so that the laying of thepipeline could proceed without delay. The molten filling did not set orharden to a sufficiently strong material within the required time toallow further processing of the pipe and the molten material would leachout into the water if the pipeline was lowered before the moltenmaterial was adequately cured.

Other known procedures have typically replaced the molten material withother types of materials. For example, one alternative material utilizedto cover the exposed portion of pipe was granular or particulate mattersuch as gravel or iron ore which did not pack solidly or uniformly. Thenelastomeric polyurethanes were injected into the mold to fill theinterstices between the granular filler materials. After the polymermaterial had reacted, the mold would be removed from the surface of theinfill.

Another known procedure involves wrapping the exposed portions of pipewith a thermoplastic sheet. The sheet overlapped the ends of the weightcoat adjacent the exposed joint and then was secured in place by screws,rivets, or straps. To increase the rigidity and impact resistance, thisjoint protection system required the installation of reinforcing memberssuch as plastic bars or tubes to the interior of the sheet. Thereinforcement bars or tubes either had to be precut and stored on thebarge or else cut to the required fitting form as part of theinstallation process on the barge. Yet another known procedure entailedfilling the lower portion of the annular space between the pipe and theplastic sheet with a material such as pre-formed foam half shells.

A more recently used technique involved encasing the pipe joint bycircumferentially wrapping a pliable sheet of cover material around theexposed portion of the joint connection. The longitudinal end portionsof the pliable cover overlapped the adjacent edges of the weightcoating, such that an annular pocket was formed about the exposed jointsection. Polyurethane forming chemicals were then injected into theempty annular space where they reacted to form high-density, open cellfoam which filled the annular space. The open cell polyurethane foam wasintended to absorb moisture and ultimately increase the ballast of thepipeline.

In many cases, vibrations during offshore operations at times couldcause the foam to vibrate, and move around, tending to separate the foamfrom the pipe, because there was no locking mechanism to hold thepolyurethane foam securely in its place. Of further concern, the outerdiameter portions of the foam were more susceptible to movement,agitation, or damage than the inner diameter portions of the foam,because the outer diameter portions might have a lower density than theinner diameter portions of the foam.

SUMMARY OF THE INVENTION

Briefly, the present invention provides a new and improved apparatus andmethod for protecting exposed pipe joints on weight coated pipelinesused in offshore applications. A pliable synthetic resin cover sleeveoverlaps a pair of weight coated sections that surround the pipeline oneach side of the pipe joint. The cover sleeve circumferentially envelopsthe pipe joint, forming an annular space between the pipe and the coversleeve and longitudinally between the pair of weight coated sections.The cover sleeve includes a number of ridges that extend inwardly fromthe sheet and form a number of chambers between the ridges. The chambersare in communication with the annular space.

A filler composition is injected into the annular space, and the fillercomposition undergoes a hardening reaction to form a high density, opencell polyurethane foam. The annular space and the chambers receive thefiller composition as it is reacting and the resultant high density,open cell polyurethane interlocks with the ridges in the cover sleevewhile hardening. The expansion of the reacting, hardening foam into thechambers produces a locking effect with the structure of the ridges andthe resultant polyurethane foam mechanically locks onto the ridges.

The present invention forms a composite system to protect the jointconnection with the foam providing continuous compressive reinforcementsand impact resistance and the cover sleeve provides puncture resistanceand protection from water jetting/post trenching operations plusabrasion resistance. The present invention further provides a betterbond between the foam and the cover sleeve, which provides for greateroverall stability and reliability.

To better understand the characteristics of the invention, thedescription herein is attached, as an integral part of the same, withdrawings to illustrate, but not limited to that, described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when thedetailed description set forth below is reviewed in conjunction with theaccompanying drawings, in which:

FIG. 1 depicts a side elevation view of a pipeline, showing two sectionsof weight coated pipe welded together at a pipe joint;

FIG. 2 is an isometric view of a pliable cover sleeve according to thepresent invention shaped in cylindrical form and used to encase theexposed joint section;

FIG. 3 is a side elevation view of a pipeline, showing a pliable coversleeve according to the present invention wrapped and sealed around theexposed joint section;

FIG. 4 is a vertical cross sectional view of the pipeline and coversleeve of FIG. 3.

FIG. 5 depicts a vertical cross sectional view taken along the lines 5-5of FIG. 4, showing a locking mechanism of the cover sleeve interlockedwith the joint-filling material.

FIG. 6 shows a plan view of an unwrapped cover sleeve like that of FIG.2 in accordance with the present invention.

FIG. 7 is a vertical cross-sectional view, like that of FIG. 5, butalong the lines 7-7 of FIG. 4.

FIGS. 8, 9, and 10 are vertical cross-sectional views of alternativeembodiments of the cover sleeve according to the present inventioninterlocked with the joint-filling material.

To better understand the invention, we shall carry out the detaileddescription of some of the modalities of the same, shown in the drawingswith illustrative but not limited purposes, attached to the descriptionherein.

DETAILED DESCRIPTION

Although the following detailed description contains many specificdetails for purposes of illustration, anyone of ordinary skill in theart will appreciate that many variations and alterations to thefollowing details are within the scope of the invention. Accordingly,the exemplary embodiment of the invention described below is set forthwithout any loss of generality to, and without imposing limitationsthereon, the claimed invention.

FIG. 1 shows a conventional, prior art weight coated pipeline 10 formedby welding together two pipe sections 12, 14, each of which is coveredby a weight coat 16, 18, respectively. The weight coat 16, 18, which isformed from concrete or another suitable material, completely covers thepipe sections 20, 22 circumferentially and longitudinally except for aportion of each pipe end 24, 26 of the pipe section 20, 22. The pipeends 24, 26 are left exposed to facilitate welding of the two pipesections 12, 14 together as sections of a pipeline. However, theseexposed pipe ends 24, 26 leave gaps of pipe not coated with weight coat16, 18 in the pipeline 10, which would be covered only by a corrosioncoating 34. The present invention is provided to protect the pipe jointof the pipe ends 24, 26 between the coated pipe sections 16, 18.

As such, the present invention provides for the utilization of a coversleeve 40 that is used to enclose and provide structural protection forthe exposed corrosion coating 34 on the pipe end 24, 26. As shown inFIG. 2, the preferred embodiment uses a cover sleeve material 40 that ispliable, yet strong, and which can be formed into a cylindrical shape tofit around the pipeline 10. The coated end portion 16 is not shown inFIG. 2 and the coated end portion 18 is shown in phantom so thatstructure of the cover sleeve 40 may be more clearly seen. The coversleeve material 40 is formed from a high-density synthetic resin,polypropylene, polyethylene, or other alternative thermoplasticmaterial. The cover sleeve 40 should be at least approximately 0.2 mmthick and may be considerably thicker if stronger support and impactresistance is desired. Water depth, pipe size, pipe weight and otherconsiderations may dictate the use of a cover sleeve 40 which is up toapproximately 12 mm in thickness. The cover sleeve 40 may be a flexibleflat sheet or may be preformed into a cylindrical shape.

An example of a suitable cover sleeve 40 is a sheet material in the formof a twin wall profile extrusion made from polyethylene or polypropylenethat is manufactured, for example, by Primex Plastics Corporation,Richmond, Ind., and which may be identified by the brand name Cor-X.Sheet materials of this type can be extruded in thickness ranges of0.006 to 0.5 inches. The sheet material used for the cover sleeve 40 ismodified in a manner described below in order to permit ease of accessof a joint infill or filler substance into the structure of the coversleeve 40 and also to permit mechanical interlocking of the protectivesleeve and the joint infill material. It should also be understood, aswill be described in greater detail below, that the structure of thecover sleeve 40 may take a number of shapes to achieve such mechanicalinterlocking.

For example, the cover sleeve material 40 may take the form of a wall 41and a wall 42 spaced from and interconnected to each other by a seriesof ribs or ridges 44 between two outer layers arranged to extend overthe length of the sleeve material 40 in a direction corresponding to thelongitudinal axis of the pipeline 10. Spaces between the walls 41 and 42and adjacent ribs or ridges 44 thus take one form of a number oflongitudinally extending tubes or passages 45. As will be set forthbelow, portions of the wall 42 are removed or opened along both thelongitudinal and transverse extent of the sheet material 40. As a resultwhen sheet material is formed into a cylindrical cover sleeve 40, thetubes, or passages 45 take the form of chambers which are in flowcommunication with an annular space 54 formed between the sleeve 40 andthe pipe 24, 26.

The pliable cover sleeve 40 is wrapped into a cylindrical shape aroundthe exposed pipe ends 24, 26 such that the outer diameter of thecylinder of cover sleeve 40 is slightly greater than the outsidediameter of the weight coat 16, 18 on the pipeline 10. Morespecifically, the inside diameter of the cylinder of cover sleeve 40 issubstantially the same as the outside diameter of the weight coat 16,18. The cover sleeve 40 should be long enough to overlap the adjacentends or edges 30, 32 of both sides of the weight coating 16, 18 byseveral inches to allow the weight coating 16, 18 to act as a structuralsupport for the cover sleeve 40. Once the cover sleeve 40 is fitted overthe adjacent edges 30, 32 of the weight coat 16, 18, the longitudinalside edges 41 and 43 of cover sleeve 40 are tightly pushed together suchthat the side edges 41, 43 overlap. The cover sleeve 40 may be tighteneddown and held in place on the ends of the weight coat 16, 18 withconventional removable cinch belts (not shown) or some other form ofsecuring structure. The outside edge 43 is then sealed to the surface ofthe cover sleeve 40 and the cylindrical, externally sealed cover sleeve50 is formed.

The cover sleeve 40 can be sealed by plastic welding an edge onto thesurface of the cover sleeve 40, forming a longitudinally extendingplastic weld 43 the entire length of the cover sleeve 40 as shown inFIG. 3. Alternative techniques for sealing such as heat fusion,riveting, gluing, taping, or banding can also be utilized to seal thecover sleeve 40.

Referring to FIG. 3, the cover sleeve 40 thus becomes the cover sleeve50, sealed by the outer wall 41 forming a protective barrier around theexposed portion of pipe 24, 26 and remaining a permanent part of thepipeline 10. The annular space 54 is thus formed around the pipe 24, 26by installing the sealed cover sleeve 50. The annular space 54 so formedbetween the pipe 24, 26 and the sealed cover sleeve 50 extendslongitudinally between the weight coat portions 16, 18.

A hole 48 is formed in the sealed cover sleeve 50, through whichreactive chemicals or compositions are injected into the annular space54 to form a joint-filler substance or composition 62. The composition62 is comprised of polyurethane chemicals of the type disclosed, forexample, in U.S. Pat. No. 5,900,195 as described below. The hole 48 maybe drilled, cut, or otherwise completed in the cover sleeve 50 tothereafter allow the yet-to-be reacted chemical or substance 62 to beinjected into the annular space 54. The hole 48 may be precut into thecover sleeve 40 prior to installation on the weight coated pipeline 10or may be cut after the sealed cover sleeve 50 is in place. The diameterof the hole 48 to be drilled is dependent upon the particular type ofmixing head used to inject the reactive chemical or substance 62.Industry standard or conventional injection heads are acceptable, butsuitable alternatives would also suffice.

As shown in FIG. 4, the annular space 54 is filled through hole 48 by amixing head with reactive chemicals or compositions, preferably thosecausing a reaction of components, such as those disclosed in U.S. Pat.No. 5,900,195. The composition 62 formed by such a reaction is, as aresult, a high-density rapid-setting polypropylene or polyurethane foamsystem 62. The foam 62 serves as a shock absorber and protects thecorrosion coating on the pipe 24, 26. Also, because the foam 62 is opencelled, it can absorb water and increase the ballast effect for thepipeline 10. Alternatively, other polymerizing or hard setting compoundssuch as marine mastics, quick setting concretes, polymers, orelastomeric compounds may be used to fill the annular space 54. Anyalternative filler substance 62 typically is quick hardening, such thatthe process of laying the pipeline 10 is not inhibited.

The preferred polyurethane or polypropylene system utilized to form theprotective high-density foam 62 in this process is a combination of anisocyanate and a polyol system. When reacted, this combination systemrapidly cures and forms high-density open celled polyurethane orpolypropylene foam 62, which resists degradation in seawater. Theisocyanate is a polymeric form of diphenylmethane diisocyanate, asmanufactured, for example, by Bayer Corp. The preferred polyol system isa mixture of multifunctional polyether and/or polyester polyols,catalysts for controlling the reaction rate, surfactants for enhancingcell formation, and water for a blowing agent. The blended polyol systemis manufactured, for example, by Dow Chemical Co., Bayer Corp., andother companies.

The preferred system produces foam 62 with a density of about 8 to 10pounds per cubic foot and has about eighty percent or greater opencells. The compressive strength of the preferred foam 62 isapproximately 200 psi or greater at 10 percent deflection and 2000 psior greater at 90 percent deflection. Reaction of the preferred systemcomponents can be characterized by a 18 to 28 second cream time, thetime between discharge from the mixing head and the beginning of thefoam rise, a 50 to 60 second rise time, the time between discharge fromthe mixing head and the complete foam rise, and a 240 to 250 second curetime, the time required to develop the polymer strength and dimensionalstability.

The cover sleeve 50 acts as a mold and receives the foam 62 in theannular space 54 and chambers 45, and further interlocks and forms amechanical bond with the foam 62 as it is cured. As shown in FIG. 4,preferably this foam 62 substantially fills the annular space 54 andchambers 45 without leaving significant void areas. Preferably, noadditional filler materials are needed to be used in conjunction withthe foam 62. The foam 62 should substantially fill the annular space 54and protrude to some extent upward through the hole 48 on the sealedcover sleeve 50.

Referring to FIG. 4, the sealed cover sleeve 50 together with the foam62 provide a protective system which protects the exposed pipe 24, 26and the corrosion coating 34 during handling and laying of the pipeline10 and continues to provide protection from damage due to drag lines ortrawler boards attached to fishing trawler nets. Further, the sealedcover sleeve 50 is not subject to the corrosion problems of priorsystems and therefore does not create an underwater hazard or a dangerto fishing nets. Additionally, the protective system provided by thepresent invention acts to deflect the high pressure water jets used tobury pipelines in shallow waters which have resulted in damage to thecorrosion coating on pipe joints protected by prior systems.

FIG. 5 depicts an axial cross section along the lines 5-5 in accordancewith a preferred embodiment of the invention, showing the cover sleeve50 filled and interlocked with the expanded, cured protective foamsubstance 62. The wall 41 of cover sleeve 50 now serves as an outer wallof the cylindrical cover sleeve 50 and thus exhibits a smooth exterior.The ribs or ridges 44 of the cover sleeve 50 thus extend radiallyinwardly from an inner surface 41 a of wall 41 in the assembledcylindrical cover sleeve 50 with the chambers 45 between them forreceiving the protective foam substance as indicated at 72. The size ofthe chambers 45 or and thus relative presence, orchambers-per-linear-foot extending in a circumferential manner aroundthe interior of sleeve 50 may be varied according to needs of aparticular pipeline. For example, the relative number may range fromabout fifty chambers per twelve inches to eighty or more chambers pertwelve inches for walls 41 and 42 of cover sleeve 50 which may range inthickness from about 2 mm through about 6 mm. Further, cover sleeves 50with wall thickness of from seven mm through twelve mm typically containabout thirty chambers per twelve inches.

As shown in FIG. 5, the structure of cover sleeve 50 has the walls 41and 42 connected by ridges 44 that hold the inner and outer wallstogether. The sleeve material is then modified such that a series oflongitudinal cuts or slices 46 are formed extending through the innerwall 42 in a direction corresponding to the axis of the pipeline 10.

In addition, circumferential bands of the inner wall 42 are removed atlongitudinally spaced positions as indicated at 74. The longitudinallyspaced positions can be relatively closer or further apart and the widthof the circumferential band removed from inner wall is usually from ⅛inch to about two inches along the interior of the cover sleeve for easeof entry of the reacting chemicals of the foam 72 into the chambers 45.The inner wall 42 may be modified such that longitudinally extendingportions or are removed between certain of the ridges 44. The inner wall42 thus may have a series of channels, as shown in FIG. 2 at 75.

The cover sleeve 50 is thus a permanent outer cladding with from aboutten to twenty circumferentially spaced ridges per square inch of theannular extent of the cover sleeve 50, forming chambers 45 in flowcommunication with the annular space 54 being filled with the chemicalsreacting to form the polyurethane foam 62. FIGS. 5, 7, 8, 9, and 10depict several possible embodiments forms suitable for the ridgesaccording to the present invention. Generally the ridges have someportion extending in a direction transverse to a radial directioninwardly from the wall 41 toward the longitudinal axis of the pipeline10 and cylindrical sleeve 50. Thus, the ridges may take various forms,generally in the form of two portions, one of which is transverse theother in their final extent or location in the cured foam filingportions 62 and 72; or extending in a curved or arcuate direction awayfrom the cylindrical inner wall; or in some combination of these orsimilar forms. It is desirable that some parts or portions of thestructure of the ridges in their final location in the cured foam extendin a direction transverse that of a radius of the cylindrical sleeve 50.In this manner, cured foam is located on each side of some portion ofthe ridges, thus interlocking with the inner structure of the ridges,sleeve rather than relying on physical bonding between cylindricalsurfaces of the foam and the sleeve, as in previous infill coatings.

The ridges 44 may be generally inverted T-shaped, as shown in FIG. 5,formed as a result of the slices 46 mentioned above with a first portion44 a of the ridges 44 extending inwardly from the inner surface 41 a ofthe outer wall 41. In the embodiment of FIG. 5, second portions 42 a and42 b of the inner wall 42 on each side of the slices 46 extendtransversely and generally substantially perpendicularly to the ridges44. The portions 42 a and 42 b thus extend perpendicularly across theridges 44 as shown in FIG. 5. As can also be seen, the ridges 44 formedin this manner have an inverted T-shape in their extent inwardly intoand interlocking engagement with the cured foam 62 and 72.

It should also be understood that the wall portions of the ridges tointerlock with the foam may take a variety of other configurations. Asexamples, the cover sleeve 50 may have ridges 47 (FIG. 8) or 48 (FIG. 9)extending inwardly therefrom in the shape or design of a loop or acurved web extending in arcuate form from the cover sheet 50. The webbedridges 47 and 48 each have a space for the components reacting andforming the foam 62 to penetrate the chambers 72 and interlock with theridges 47 and 48. The arcuate segments 48 (FIG. 9) are circumferentiallydisposed along the inner wall surface 41 a of the cover sheet 50, withalternate sets of the arcuate segments 48 formed with inner end portionsspaced from each other to form a space 48 b for entry of foam into thechambers 54. In the embodiment of FIG. 8, the ridges 47 extend inwardlyfrom the cover sleeve 50 in a somewhat comparable manner as docorrugation layers formed in cardboard materials. In the embodiment ofFIG. 10, ridges 49 extend inwardly from the cover sleeve 50 in agenerally hook-shaped manner. In each of the embodiments of the presentinvention, the chemicals reacting and causing the form 62 to be formedare able to enter the chambers 72 through the spaces shown betweenadjacent ridges or adjacent ones of the various ridges extendinginwardly from the cover sleeve 50.

Turning now in greater detail to the embodiment shown in FIG. 8, theridges may be formed as a series of arcuate segments extending inwardlyfrom the cover sheet. The arcuate segments may take the form ofundulating or wave-shape in vertical cross-section circumferentiallydisposed along the inner surface 41 a of the wall 41 of cover sheet 40,as shown at 47 in FIG. 8, with a central portion 47 a mounted with orformed as an integral portion of the outer wall 41 and having two curvedor arcuate segments 47 b and 47 c extending inwardly to be received inand interlock with the chemicals as they react to cause formation of thecured foam 62. The arcuate segments 47 b and 47 c may result fromforming longitudinal cuts or slices, leaving spaces 47 d in awave-shaped sheet of material 47. Alternatively, the ridges may be inthe form of a number of separate arcuate segments 47 mounted at spacedlocations as shown at 47 d from each other.

Further, as has been discussed, the ridges may take the form of a seriesof arcuate segments, such as curved wall members 48 (FIG. 9). As shownin detail in FIG. 9, the curved wall members 48 are formed extending inarcuate form circumferentially disposed and extending inwardly frominner surface 41 a of the cover sheet with alternate sets of the curvedwall members 48 having end portions 48 a spaced from each other as shownat 48 b to form chambers 45 in the flow communication with the annularspace 54 to receive the foam 62 and 72.

Further, in another embodiment shown in FIG. 10 ridges according forprotective covers for joint infill according to the present inventionmay take the form of inverted-L or hook shape as shown at 49 in FIG. 10,with a first portion 49 a extending inwardly from the inner surface 41 aof the outer wall 41. A second portion 49 b of the ridge 49 extendstransversely or perpendicularly to the first portion 49 a, with anoptional third portion 49 c extend generally radially inwardly to thewall 41, leaving a space 71 providing flow communication for the foam72.

It should also be understood that in the embodiments of FIGS. 8-10,circumferential bands as indicated at 74 and, where applicable, channels75, are typically present to provide flow communication so that the foam62 as it is forming and cures penetrates and fills the chambers 45 asshown at 72. The resultant foam in chambers 45 engages, interlocks, andsubstantially bonds with the ridges 70 in the interior of the coversleeve 50. As the foam 62 reacts to fill the annular space 54, it alsoexpands and substantially penetrates the chambers 45 formed by theridges 44. The present invention provides thus for a better mechanicalbond at the interface between the polyurethane or polypropylene foam 62and the cover sleeve 50.

It should be understood that the ridges 44 extending inwardly from thecover sleeve 50 may take a number of forms according to the presentinvention. For example, the invention cover sleeve 50 need not have bothlongitudinal cuts 46 and circumferential bands 74 for flow communicationfrom the annular recess 54 into the chambers 45. The cover sleeve 50 maythus be provided with only longitudinal cuts 46 or circumferential bandsin inner wall 42 for fluid communication.

It should be understood that the Figures of the present invention aregenerally not drawn according to scale with respect to the relativesizes of various structural elements shown. Rather, the relative size ofsome of the structural elements are enlarged in comparison to otherstructure in order to more clearly illustrate the features of suchstructural elements. For example, in FIGS. 5 and 7-10, the ridges areenlarged in comparison to cover sleeve 50 in order to more clearlyillustrate the structure of the ridges and their interlocking with thefiller foam substance 62.

From the foregoing, it can be seen that the present invention providesan apparatus and method for protecting the corrosion coating 34 onexposed pipeline joints such as 12, 14 on weight coated pipelines 10used in offshore applications. The cover sleeve 50 and the foam 62 worktogether to protect the joint connection. The aforementioned methodologyallows quick installation on a lay barge where pipeline sections 24, 26are being welded together for offshore installation. The presentinvention further provides a locking mechanism to secure the foam 62inside the cover sleeve 50, thus preventing the foam 62 from subsidenceaway from the cover sleeve 50, or movement or agitation relative to thepipe in a circular or circumferential manner around the pipe, whichotherwise may occur from vibrations occurring during offshoreoperations.

Moreover, because the outer diameter portions of the foam 62 may have alower density than the inner diameter portions of the foam 62, priorembodiments in the art indicate that the outer diameter portions of thefoam 62 are more susceptible to movement or agitation relative to thepipe than the inner diameter portions of the foam 62. For this reason,the positioning of the locking mechanism on the outer side of the foam62, rather than on the inner side of the foam 62, should be regardedwith considerable importance.

The invention can be used for pipe joints that are part of a pipelinelocated on the floor of a body of water. The invention can be used inmany applications, including use as a deep water insulation jointinfill, and as a deep sea abrasion sleeve. In this manner, a better,more secure, and more stabilizing bond is formed between the foam 62 andthe cover sleeve 50, which provides greater overall stability andreliability during offshore operations. Thus, the present inventionimproves the performance of pipelines where pipe ends 24, 26 are weldedtogether on pipelines coated with concrete weight coating 16, 18 andinstalled on the seabed in large bodies of water.

The invention has been sufficiently described so that a person withaverage knowledge in the matter may reproduce and obtain the resultsmentioned in the invention herein Nonetheless, any skilled person in thefield of technique, subject of the invention herein, may carry outmodifications not described in the request herein, to apply thesemodifications to a determined structure, or in the manufacturing processof the same, requires the claimed matter in the following claims; suchstructures shall be covered within the scope of the invention.

It should be noted and understood that there can be improvements andmodifications made of the present invention described in detail abovewithout departing from the spirit or scope of the invention as set forthin the accompanying claims.

1. A method for protecting a pipe joint of a pipeline, comprising:wrapping a cover sheet circumferentially about the pipe joint, the coversheet having a plurality of chambers formed along an inner surface by aplurality of ridges extending inwardly; forming an annular space betweenthe pipe joint and the wrapped cover sheet with the chambers between theridges in communication with the annular space; introducing into theannular space a joint filling material in the form of chemicals whichare adapted to react and form a high density, open cell polyurethanefoam; allowing the chemicals of the joint filling material to react andform a high density, open cell polyurethane foam; allowing the reactingchemicals of the joint filling material to expand and be contained inthe annular space and the chambers; and interlocking the high density,open cell polyurethane foam formed by polyurethane chemicals in theannular space with the ridges on the cover during the step of allowingthe reacting chemicals to expand and be contained in the annular spaceand the chambers.
 2. The method of claim 1, wherever the pipeline has aplurality of pipe joints along its length, and wherein: the step ofwrapping comprises wrapping cover sheets about the individual ones ofthe plurality of paper joints,
 3. The method of claim 2, wherein: thestep of forming an annular space comprises forming an annular spacewithin the wrapped cover sheets.
 4. The method of claim 3, wherein: thestep of introducing comprises introducing a joint filling material intothe annular space within the wrapped cover sheets.
 5. The method ofclaim 1, wherein portions of the ridges are removed along thelongitudinal extent of the annular space between the coated pipesections, and further including the step of: allowing the reactingchemicals to flow into the areas where the portions of the ridges areremoved.
 6. The method of claim 1, wherein portions of the inwardlyextending ridges are removed around the annular space formed about thepipe joint by the cover sheet, and further including the step of:allowing the reacting chemicals to flow into the areas where theportions of the inwardly extending ridges are removed.
 7. A pipelinewith at least one protected pipe joint along its length, comprising: aplurality of coated pipe sections located on the floor of a body ofwater, adjacent ones of the coated pipe sections being connectedend-to-end to form the pipe joint; a pliable synthetic resin cover sheetmounted on the pipe joint and overlapping the coated pipe sections andenveloping the pipe joint, forming an annular space about the pipe jointbetween the coated pipe sections; the pliable synthetic resin coversheet having a plurality of ridges extending inwardly from the coversheet into the annular space about the pipe joint and forming aplurality of chambers between the ridges; the chambers being in flowcommunication with the annular space; the annular space containing ajoint filling material of a high density, open cell polyurethane foamformed by polyurethane chemicals extending circumferentially around andenclosing the pipe joint; the chambers containing a joint fillingmaterial extending outwardly to the cover sleeve from the joint fillingmaterial in the annular space; and the joint filling materialinterlocking with the ridges in the cover sheet to improve the bondbetween the joint filling material and the cover sheet protecting thepipe joint.
 8. The apparatus of claim 7, wherein portions of the ridgesare removed along the longitudinal extent of the annular space betweenthe coated pipe sections for flow of the polyurethane chemicals into thechambers.
 9. The apparatus of claim 7, wherein portions of the inwardlyextending ridges are removed around the annular space formed about thepipe joint by the cover sheet for flow of the polyurethane chemicalsinto the chambers.
 10. The apparatus of claim 7, wherein the ridgesextend along the longitudinal extent of the annular space between thecoated pipe sections.
 11. The apparatus of claim 7, wherein a firstportion of the ridges extends inwardly from the cover sheet.
 12. Theapparatus of claim 7, wherein the ridges comprise curved wall membersextending in arcuate form from the cover sheet.
 13. The apparatus ofclaim 7, wherein the ridges comprise wall members having a web-shape incross-section in their inward extent into the annular space.
 14. Theapparatus of claim 7, wherein the ridges comprise wall members having ahook-shape in cross-section in their inward extent into the annularspace.
 15. The apparatus of claim 7, wherein the ridges comprise aseries of arcuate segments extending inwardly from the cover sheet. 16.The apparatus of claim 7, wherein alternate sets of the series ofarcuate segments are formed with inner end portions spaced from eachother to form chambers.
 17. The apparatus of claim 7, wherein a portionof the ridges extends radially inwardly from an inner surface of thecover sheet.
 18. The apparatus of claim 7, wherein the cover sheetcomprises an inner cover wall and an outer cover wall.
 19. The apparatusof claim 18, wherein the ridges extend between the inner cover wall andthe outer cover wall.
 20. The apparatus of claim 7, wherein the pliablesynthetic resin cover sheet comprises a polyethylene material.
 21. Theapparatus of claim 7, wherein the ridges are spaced from each otherabout a circumferential extent on an inner surface of the pliablesynthetic resin cover sheet.
 22. The apparatus of claim 7, wherein theridges extend longitudinally in a direction of an axis of the pipe. 23.In a pipeline beneath a body of water having a pipe joint formed betweenadjacent joined end sections of weight coated pipe, the improvementcomprising: a protective sleeve enclosing the joined pipe end sections,the sleeve comprising: a pliable synthetic resin cover sheetcircumferentially enveloping the joined pipe end sections, forming anannular space about the pipe end sections; a plurality of ridgesextending inwardly from the pliable synthetic resin cover sheet andforming chambers between the ridges; the chambers being in flowcommunication with the annular space; and the annular space and thechambers receiving a high density, open cell polyurethane foam formed bypolyurethane chemicals interlocking with the ridges to form theprotective sleeve to improve the bond between the joint filling materialand the cover sheet protecting the pipe joint.